Lightweight BCGs

[Frack N Cylons]

What are your experiences? Pros? Cons?

I recently rebuilt my 3 gun rifle, this time with an SA AGB and it has made a noticeable difference in how flat the gun shoots. Will a lightweight BCG make that much more difference?

My #1 priority would be reliability. Longevity would be up around #2, so no aluminum.

I see some out there for $400. I see some for $100.

I’m perfectly fine leaving a milspec BCG in there, but I may get an itch to change things up.

 

[barf]

What are your experiences? Pros? Cons?

I recently rebuilt my 3 gun rifle, this time with an SA AGB and it has made a noticeable difference in how flat the gun shoots. Will a lightweight BCG make that much more difference?

My #1 priority would be reliability. Longevity would be up around #2, so no aluminum.

I see some out there for $400. I see some for $100.

I’m perfectly fine leaving a milspec BCG in there, but I may get an itch to change things up.

Just cut some go fast slots into the milspec one 😂

 

[maven]

short answer is yes. secondary impulse is more important to keeping a dot on target.

the brake does most of the work initially. removing mass in the carrier and/or buffer and reducing the spring rate tunes the "thunk" you feel when it goes back into battery causing the rifle to dip. if your brake keeps the gun flat on the rearward stroke, a low mass carrier is what keeps it flat on the forward stroke. this is often over looked.

the $100 brownells lightweight carriers are a cheap copy of cryptic coatings light weight carriers. both are steel. both work fine.

solid titanium carriers are the top of the line and cost around $300 for just the carrier but are super light and have fancier coatings.

10oz total weight of bcg and buffer with a reduced power spring is the sweet spot, imo. this can easily be achieved with the cheap steel ones. going to titanium you can get down to about 9.5oz. chasing it past that isnt worth the return. you still need some mass to pick up and chamber a round on a hot dirty game gun.

only con is money. but all shooting sports will "hundred dollar you to death"

if you aleady have adjustable gas you are missing out by not finishing the tune.

 

[NKD]

Maven covered it well. It's kind of like the icing on the cake.

I have three different guns with lightweight recoil systems. Went pretty cheap on all of them. Have used AIM and Brownells lowmass BCG's coupled with Taccom delrin ultralight buffers and Sprinco yellow -10% spring, with various adjustable gas blocks. All with great success. They definitely shoot very flat and feel great.

If money were no object I would likely use the whole JP system.

 

[NKD]

For just over a hundred bucks, these are worth a try:

M16 5.56 LIGHTWEIGHT BOLT CARRIER GROUP | Brownells

The Brownells M16 Lightweight Bolt Carrier Group is purpose-built for AR-15 owners looking to improve aspects of their rifle with a simple component swap, eliminating the need for major component replacement or amateur gunsmithing work. The Browne...

prod.brownells.com

Then add a spring ($20) and an empty carbine buffer. Low mass on the cheap.

 

[Studentofthegun]

I don't have anything to add but I'll simply say to listen to @NKD cause I traded some knife or something for his old lightweight / light recoil setup and it is black magic. Works extremely well.

 

[NCLivingBrit]

Just cut some go fast slots into the milspec one 😂

 

[Lucky63]

RTB Complete Lightweight BCG - Black Nitride & RTB Reduced Power Carbine Buffer Spring - RP YELLOW

Veteran-owned and operated, we utilize a live inventory system to give you the latest and best in replacement AR-15 parts and accessory upgrades as well as Glocks. Choose from the most reputable brands to build an AR-15 or Glock pistol that's entirely your own. Free shipping available on select...

www.righttobear.com

For some reason it’s almost 1/2 the price of just buying the same BCG. I’m tempted myself but mine is tuned for full auto BCG, carbine buffer (3.0 oz), and standard spring. Honestly, I don’t believe in trying to fix what ain't broke. 🤷🏼

Note: RTB has some great deals right now.
$45 pencil barrels and more 👍🏻

 

[Frack N Cylons]

RTB Complete Lightweight BCG - Black Nitride & RTB Reduced Power Carbine Buffer Spring - RP YELLOW

Veteran-owned and operated, we utilize a live inventory system to give you the latest and best in replacement AR-15 parts and accessory upgrades as well as Glocks. Choose from the most reputable brands to build an AR-15 or Glock pistol that's entirely your own. Free shipping available on select...

www.righttobear.com

For some reason it’s almost 1/2 the price of just buying the same BCG. I’m tempted myself but mine is tuned for full auto BCG, carbine buffer (3.0 oz), and standard spring. Honestly, I don’t believe in trying to fix what ain't broke. 🤷🏼

Note: RTB has some great deals right now.
$45 pencil barrels and more 👍🏻

My rifle ran awesome yesterday at the 3 gun match, so let's rip it apart and change stuff!

I wanted to get that match out of the way before changing anything.

This deal looks worth trying out, just to see if I like it.

 

[maven]

Take that kit and pair it with a carbine buffer that has the steel weights swapped out with aluminum weights. (You can order individual aluminum weights from kak) That will put you right at the magic 10oz mass. Close your gas block all the way and load one round at a time adding gas until it locks back on empty.

If you dont want to tune the buffer weights a standard 3oz buffer will be fine and youll still feel a huge difference. Some folks like empty buffer bodies but I have tested enough variations to believe there needs to be something in the buffer itself. Your preference may vary.

If you really want to smooth it out swap the milspec gas rings with a JP one piece gas ring.

You won't regret it.

 

[Jerzsubbie]

Maven covered it well. It's kind of like the icing on the cake.

I have three different guns with lightweight recoil systems. Went pretty cheap on all of them. Have used AIM and Brownells lowmass BCG's coupled with Taccom delrin ultralight buffers and Sprinco yellow -10% spring, with various adjustable gas blocks. All with great success. They definitely shoot very flat and feel great.

If money were no object I would likely use the whole JP system.

This (AIM NiB BCG, Taccom buffer, Springco yellow, SLR gas block) is what I’ve used in my 2-gun rifle for years, shoots incredibly soft, tuned to Wolf/Tula, and doesn’t cost an arm and a leg for the entire setup either. The only thing I would change is to use a bleed off type gas block (can’t recall the name of the good one at the moment).

 

[Frack N Cylons]

I am having trouble accepting the low mass buffer weights. Isn’t their purpose to counter bolt bounce?

Since the BCG itself is lower mass, is the need for a buffer to counter bolt bounce less important?

Is bolt bounce even a problem in a semi auto gun?

 

[Frack N Cylons]

The only thing I would change is to use a bleed off type gas block (can’t recall the name of the good one at the moment).

I’m using a Superlative Arms. I like it so far. I’m thinking I can count clicks and record that data if I want to go back to a milspec BCG and buffer/spring setup.

 

[Jerzsubbie]

It’s been a long time since I’ve researched this but your buffer weight is based on the amount of gas being used to cycle the action. Blowbacks use a ton of gas so super heavy buffer; overgassed carbine, heavier buffer.

In the case of my build, I’ve tuned the gun to run on weak wolf/Tula so that there isn’t a ton of excess gas (2 clicks above where it stops locking back on an empty mag). With that little gas, a lightweight buffer and spring works quite well. The downside is reliability. There is very little margin for a dirty gun, carbon fouled gas block adjustment screw, an extra weak round, etc.

 

[Jerzsubbie]

I’m using a Superlative Arms. I like it so far. I’m thinking I can count clicks and record that data if I want to go back to a milspec BCG and buffer/spring setup.

Yes, that’s the one!

Btw you’re welcome to try out my AIM BCG and Taccom buffer setup. Unfortunately that gun never gets shot these days so it’s no big deal.

 

[maven]

I am having trouble accepting the low mass buffer weights. Isn’t their purpose to counter bolt bounce?

Since the BCG itself is lower mass, is the need for a buffer to counter bolt bounce less important?

Is bolt bounce even a problem in a semi auto gun?

Bolt bounce is really only an issue when we're talking about the cyclic rate obtained with full auto. most shooters (and by most i mean nearly all) can't run a semi auto fast enough for bolt bounce to matter even if it is occurring every time the carrier goes into battery. we're talking about fractions of a second. you are correct that bolt bounce is a non issue in semi auto.

low mass carrier + low(er) mass buffer is important when using a weaker spring. less mass for the spring to push home while stripping off the next round. dropping the weight of the carrier without also paring down the buffer weight will still be better than neither but the tune is only half way done.

The SA gas block is a great block. You will want to keep it in restrictive mode, though. Bleed off is designed for when suppressors are added to the system and the port pressure and dwell time go through the roof. In a tuned rife with low mass components getting pushed by a standard 16in mid length gas system (assuming a reasonable gas port to start) you can choke the gas way down and it will run fantastically. As a plus, using restrictive mode over bleed off you'll see a small boost in fps. no need to vent gas when the port pressure and dwell haven't changed.

 

[NKD]

This (AIM NiB BCG, Taccom buffer, Springco yellow, SLR gas block) is what I’ve used in my 2-gun rifle for years, shoots incredibly soft, tuned to Wolf/Tula, and doesn’t cost an arm and a leg for the entire setup either. The only thing I would change is to use a bleed off type gas block (can’t recall the name of the good one at the moment).

I'm definitely going with Superlative or Riflespeed gas block next time.

 

[Frack N Cylons]

Bolt bounce is really only an issue when we're talking about the cyclic rate obtained with full auto. most shooters (and by most i mean nearly all) can't run a semi auto fast enough for bolt bounce to matter even if it is occurring every time the carrier goes into battery. we're talking about fractions of a second. you are correct that bolt bounce is a non issue in semi auto.

low mass carrier + low(er) mass buffer is important when using a weaker spring. less mass for the spring to push home while stripping off the next round. dropping the weight of the carrier without also paring down the buffer weight will still be better than neither but the tune is only half way done.

The SA gas block is a great block. You will want to keep it in restrictive mode, though. Bleed off is designed for when suppressors are added to the system and the port pressure and dwell time go through the roof. In a tuned rife with low mass components getting pushed by a standard 16in mid length gas system (assuming a reasonable gas port to start) you can choke the gas way down and it will run fantastically. As a plus, using restrictive mode over bleed off you'll see a small boost in fps. no need to vent gas when the port pressure and dwell haven't changed.

Good info, thanks.

On the SA gas block, bleed off mode is acceptable for an unsuppressed rifle. SA actually recommends setting the rifle up unsuppressed.

One of greatest benefits of bleed off over restriction is that the gas block is much less likely to seize, suppressed or not.